Publication Date:
2014-12-05
Description:
The dielectric, magnetic, and magnetodielectric properties of Ca 2 Fe A O 5+δ ( A = Al, Ga) ceramics were investigated together with their crystal structures. Rietveld refinement of the X-ray diffraction data indicated that the space group of the Ca 2 FeAlO 5+δ ceramic was Ibm 2, whereas that of the Ca 2 FeGaO 5+δ ceramic was Pcmn . Dielectric relaxation above room temperature, originating from the Maxwell–Wagner effect and polaronic hole hopping between Fe 3+ and Fe 4+ ions, was observed in both ceramics. Weak ferrimagnetic behavior was identified from the magnetic-field-dependent magnetization in these ceramics, which was attributed to the non-cancelled spins of the antiferromagnetic-ordered Fe 3+ and Fe 4+ ions. An intrinsic, giant, room-temperature magnetodielectric coefficient of up to −23.3% was achieved in the Ca 2 FeAlO 5+δ ceramic at 50 MHz, which was attributed to the suppression of charge fluctuations of Fe 3+ and Fe 4+ ions in the magnetic field.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
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